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Trafomatic Audio Luna LCR phonostage

These days I am looking into tube phono stages a lot. Especially phonostages which are within $5-6k and that can serve in a serious high end system. While I know that solid state phonostages have traditionally been known for their low noise and high dynamic presentation, I still believe that harmonics that tubes preserve (and SS throw away) can be a great asset to the end result i.e music. And if well designed tubes can do low noise and high dynamic range too.

I know that an all-tube 70db phono gain is a steep challenge and while there are manufacturers who have attempted it (e.g Aesthetix, NVO), the response from the users have been mixed. I am more for the conventional approach of using a top quality tube MM stage with a top quality SUT (matched to the cartridge) or FET stage. In this realm there are not many serious options in the $5k range if I look around. The few that I have looked at are:

Allnic H1500 II SE
Luxman EQ-500
EAR 88PB
Herron VTPH-2 
Leben RS-30EQ

Then there are some full function tube preamps which do have very competitive in-built phonostages like the Shindo Masseto, Manley Steelhead, CAT Ultimate etc.

Here is another one that looks like very good contender for a top quality tube phonostage in this budget:
http://www.trafomaticaudio.com/products/luna/

An LCR design using an all-out tube design with interstage transformers and output transformers, so absolutely no capacitor in the path. MC stage is handled by Lundahl 1941 amorphous cobalt core SUTs. This looks like a no compromise assault for this price category. I have not yet heard it but whenever I have heard Trafomatic products I have always come back with a smile. They have been consistently balanced and musical without any typical voicing artifacts. They never sounded like a product that has been hastily put together or built out of a garage. For a tube amp I have never heard them having any hum or noise issues. In fact I have always found his amps to have a very matured sound. In that regards this is a phono stage I am excited about. If anyone gets an opportunity to hear them, do share your thoughts here.
pani

Showing 5 responses by lewm

lewm
13,476 posts
 
The Luna is an interesting product that I have not seen before.   It must be a new model, because I had been intrigued by their earlier phono circuit which used a pentode as phono input tube, and RIAA correction was accomplished by a circuit located between the plate of the pentode and B+.  This is a very novel idea.  Now it seems that the designer seeks to cash in on the popularity of LCR phono correction, which is fine and can sound great too.  I am not so crazy about all those transformers in the signal path, but hearing is believing.  Note too that using a step-up transformer for MC sets an upper limit on the load resistance seen by the cartridge, as in this case it's 100R and down from there.  I don't usually blow the horn for stuff I personally own, but for a full-function preamplifier, you might also consider the Atma-sphere MP1, which has enough inherent phono gain such that you don't need a SUT.  The only thing I would criticize it for is relative lack of flexibility and the fact that it actually has too much gain for MM or MI cartridges, some of which I like a lot.  That said, the MP1 blows away every other phono stage I have used for MC cartridges, in my main system.  I just bought a Steelhead for my "other" system.  It's too soon to say which is better between those two, but my money is on the MP1.  The Steelhead is MUCH more flexible as regards phono; the MP1 is MUCH more of a true full-function preamplifier, however, in that it offers multiple hi-level inputs, phase reversal, etc, etc.  

lewm
13,476 posts
 
Pani, I think I was misunderstood.  I did not mean for my comments to imply that transformer-coupling cannot work well and sound great. My point was that using a SUT between a LOMC cartridge and a phono stage per se limits the impedance with which you can load the cartridge. This is only because the turns ratio of the SUT determines the impedance "seen" by the cartridge looking in to the phono input. Case in point, the Luna starts at 100R and goes down from there.  Most LOMCs will work fine into a 100R load, but lately it has been my observation that many LOMCs can sound even better with less of a load.  I spent the last two nights, in fact, listening to two different LOMC cartridges with load 47K ohms. I found that I slightly preferred that to 100R or even 1000R. (Load is selectable on my MP1.)

In the case of the Luna, and without having seen the schematic, I wager that the interstage transformer was necessary for the sole purpose of reducing the output impedance of the stage driving the LCR correction circuit; the impedance has to match that of the LCR module, and most require 600R, although in recent years LCRs that need to see higher impedances have been devised, when the needed inductors can be precisely wound.  This is not necessarily a bad thing; it just is what it is.

lewm
13,476 posts
 
Pani, Also, prepare yourself for the onslaught of the Herron-lovers. There are many of them here, so many that I don’t doubt its excellence. Keep in mind that the Herron uses an "old fashioned" CR type of RIAA correction and no transformers in the signal path. There are many paths to Nirvana.

(I still want to hear the older Trafomatic phono that places the RIAA correction in the plate circuit of the input tube.)

Tom, Have you posted the schematic of your "interstage LCR" phono design? I certainly remain interested in LCR and even LR phono correction.

lewm
13,476 posts
 
And I think it's a mistake to think that any particular topology is per se going to sound great regardless of who designed it and regardless of parts quality.  In your case, you got chokes made by Dave Slagle, i.e., the highest quality I can imagine.  Do we know that the Trafomatic sourced their chokes from an equally prestigious source?   Plus, you describe your phono stage that is off the charts for more reasons than just the quality of your chokes, or the 7K value of your LCR that permits a much more simpatico tube circuit than does the typical 600R LCR module.  In a commercial product, and given Pani's lack of DIY expertise, I would almost say that simpler (CR correction) is likely to be better, on a dollar for dollar basis, but of course there are exceptions to any rule.  For sure, the Trafo deserves an audition.  By the way too, not everyone is crazy about interstage transformers, even those who like transformers and tubes. I'm just saying.  I personally have no opinion on that score (use of interstage transformers per se), because I do not feel qualified to have one.
lewm
13,476 posts
 
Tom, I think I said this before, but judging from your follow-up post, you did not "receive" my message.  I keep an open mind on transformers in audio.  I don't necessarily think interstage transformers are "bad", but perhaps that is the audio transformer function of which I am most skeptical.  In my response, I was merely pointing out that some who know more about the advantages and disadvantages of IS transformers than I do have written about the disadvantages, and I was influenced by what I have read.  But this hasn't caused me to dismiss the idea. t would be eager to hear your phono stage any time.

Pani, I know what a SUT does. However, the SUT will affect the impedance seen by the cartridge according to the square of the turns ratio.  So, if your SUT is providing a 1:10 voltage step-up, then the impedance seen by the cartridge running into a SUT in series with a typical MM phono stage will be 470R (47,000 ohms divided by 100).  My point was that lately I have been finding that I like to run my LOMC cartridges into more like a 47K ohm load (i.e., unloaded).  To achieve that with a 1:10 SUT, I would need a 4.7M resistor across the secondaries.  Since that resistor also serves as the grid resistor of the input tube, problems with grid current might be created by using such a large value grid resistance.  (It would probably work OK with certain tubes, but not all.) Also, I do not agree that using a SUT necessarily avoids problems related to "ringing" that might otherwise be encountered if using an active gain stage with an LOMC (unless that gain stage is intrinsically flawed in design).  There's a nice white paper on using Zobel networks to tame the response with SUTs, on the Jensen website.

I was interested to read your thoughts on the Herron. I've never heard one, but as you know, there are many devoted users here.

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